(a) Field of the Invention
The present invention relates to a roaming service system for the global system for mobile communications (GSM) service subscribers in code division multiple access (CDMA) service areas, and methods for registering locations, and transmitting and receiving signals and short messages using the roaming service system. More specifically, the present invention relates to a roaming service system for a GSM service subscriber who installs a subscriber identity module (SIM) card in a CDMA terminal and receives the roaming service in the CDMA service areas, and methods for registering locations and transmitting and receiving signals and short messages using the roaming service system.
(b) Description of the Related Art
Recently, as the demand for mobile communications has greatly increased, requests for global roaming services that enable users to telephone using a single telephone number all over the world have increased.
Presently, when a GSM service subscriber who lives in another country comes to Korea and wishes to receive the CDMA service, the user rents a new terminal at a service agency or an airport lounge and obtains a new subscriber phone number.
Particularly in the GSM method, the subscriber installs a SIM card which stores the subscriber""s profile in the subscriber""s terminal. In this kind of mobile communication using the SIM card, the user can borrow a SIM-support terminal in any country that provides the GSM service, install the user""s SIM card in the terminal and use the user""s own telephone number. However, in Korea, which provides the CDMA service, the GSM subscribers cannot use their own phone numbers using the SIM card.
Recently, countries that have adopted the CDMA method have gradually started using the advantages of the SIM card by adopting a user identity module (UIM) card which is similar to the SIM card. Accordingly, CDMA terminals that use the UIM card are being developed. Even though the size of the SIM card is identical with that of the UIM card and the SIM card can be installed in the CDMA terminal, since the CDMA service method is different from the GSM service method, the user cannot receive mobile communication service using the CDMA terminal with a SIM card installed.
It is an object of the present invention to provide a roaming service on the CDMA network by installing the GSM-type SIM card into the CDMA terminal.
In one aspect of the present invention, a roaming service system in a CDMA service area for a GSM service subscriber comprises: a CDMA system comprising a CDMA home location register (HLR) storing information on subscribers"" locations and services, a CDMA mobile switching center (MSC) connected to the CDMA HLR and accessing calls, and a CDMA terminal wirelessly connected to the CDMA MSC and capable of having a subscriber identity module (SIM) card removably installed therein; a GSM system comprising a GSM HLR storing information on the subscribers"" locations and services, a GSM MSC connected to the GSM HLR and accessing calls, an authentication center (AuC) connected to a GSM network and authenticating terminals, and a GSM terminal wirelessly connected to the GSM MSC; and an international roaming gateway system (IRGS) connected between the CDMA system and the GSM system and converting signals to execute signal communications between the systems, and when a subscriber of a service provided by the GSM system moves to an area in which the subscriber can use the service provided by the CDMA system and installs the subscriber""s SIM card in the CDMA terminal, transmissions of predetermined data necessary for a GSM authentication by the CDMA system being executed using a CDMA message so that tasks of initial location registration of the GSM service subscriber, a location registration when the location is modified, sending and receiving calls with other subscribers, and a short message service (SMS) are enabled.
In another aspect of the present invention, in a method for registering a location when a subscriber of the GSM system service moves to a CDMA system service area and installs a SIM card in a CDMA terminal and roams to the CDMA system service in a system comprising a CDMA system comprising a CDMA MSC accessing calls, and a CDMA terminal wirelessly connected to the CDMA MSC and capable of having the SIM card removably installed therein; a GSM system comprising a GSM HLR storing information on the subscribers"" locations and services, and an AuC connected to a GSM network and authenticating terminals; and an IRGS connected between the CDMA system and the GSM system and converting signals to execute signal communications between the CDMA and GSM systems, a method for registering a location when a GSM service subscriber roams to the CDMA service comprises: (a) the CDMA terminal requesting a location registration from the CDMA MSC; (b) the CDMA MSC, when receiving the location registration request, authenticating the GSM subscriber via the IRGS that transmits data to the CDMA terminal using a CDMA message in cooperation with the GSM system and the data needed for the GSM authentication; and (c) registering the GSM subscriber via message transmissions between the IRGS and GSM HLR when the authentication of the GSM service subscriber is completed.